Chemistry Reference
In-Depth Information
9.1 INTroDuCTIoN
9.1.1 Definition of Probiotics
As defined by the Food and Agriculture Organization of the United Nations
(FAO) and the World Health Organization (WHO) in 2002, probiotics are: “Live
microorganisms which when administered in adequate amounts confer a health
benefit on the host.” Probiotics (literally “for life”) are friendly bacteria or yeasts
and are a concept in contrast to antibiotics. Lactobacilli and bifidobacteria are the
most common probiotic bacteria, but the yeast
Saccharomyces cerevisiae
and some
Escherichia coli
strains are also used as probiotics. Probiotics can be found in the
form of food or dietary supplements in the United States. Potential health benefits
from probiotics may vary depending on the type of probiotics consumed.
9.1. 2
Lactobacillus
Lactobacillus
is a genus of Gram-positive, nonspore-forming, catalase-negative,
facultative anaerobic or microaerophilic rods, which commonly produce lactic acid
as their major metabolite. Lactobacilli are widespread in nature, found in human and
other animal digestive systems. At present, more than 125
Lactobacillus
species have
been identified. Some
Lactobacillus
species aid in production of “fermented foods,”
such as pickles, kimchi (kimchee), cheese, yogurt, and fermented milk. Lactobacilli
have been used to enhance the storage stability of foods and improve taste, but
recently attention has been paid to their beneficial effects on human health.
9.1.3
Lactobacillus casei
Lactobacillus casei
is broadly distributed in nature and isolated from dairy prod-
ucts, silage, and the intestinal tracts of various animals. This particular species,
L.
casei,
is suggested to have a wide range of pH and temperature. The most common
application of
L. casei
is industrial, specifically for dairy production.
Lactobacillus
casei
is typically the dominant species of nonstarter lactic acid bacteria used in the
manufacture of fermented dairy beverages.
Several stains of
L. casei
have been found, and many aspects of their biological
activities have been intensely studied.
9.1.4
Lactobacillus casei
strain shirota
In 1930, Dr. Minoru Shirota was at the Microbiological Laboratory of Kyoto
Imperial University's School of Medicine, where he successfully cultured a bacterial
strain that was able to survive throughout the intestines. This strain, selected from
a large collection of lactic acid bacteria, was later named
Lactobacillus casei
strain
Shirota and was found to act as a probiotic agent (Figure 9.1).
